Intake control valve

ABSTRACT

Control arrangements for the induction system of an internal combustion engine having a control valve in the induction passage which is moveable between an opened position wherein the flow into the combustion chamber is unrestricted and in a first direction and in closed position wherein the flow into the combustion chamber is restricted to accelerate the velocity of the charge entering the combustion chamber and change its direction from the first direction. Optimum positions are set for the control valve in response to engine speed and engine load but the control valve is held in a closed position when the engine speed is below a predetermined speed and regardless of the load and is also held in an opened position when the engine speed is above a second predetermined speed and regardless of load. Various routines are shown for positioning the control valve to accommodate catalytic convertor warm up, sudden acceleration or deceleration conditions and other transient conditions. In addition, the spark timing for the engine is also controlled in response to the operation of the control valve.

This application is a divisional of U.S. patent application Ser. No.08/091,605, filed Jul. 13, 1993, by the same inventor.

BACKGROUND OF THE INVENTION

This invention relates to an intake control valve for an internalcombustion engine and more particularly to an improved method ofoperating such a control valve so as to optimize engine performanceunder a wide variety of conditions.

As is well known, many facets in the design and construction of internalcombustion engines represent a compromise between maximum efficiency,maximum power and good running under widely varying conditions. Theinduction system is a prime example where such compromises may berequired. When running at low speeds and low loads, it is desirable toinduce a large turbulence to the charge that enters the combustionchamber so as to insure rapid flame propagation and full combustion.Although a wide variety of constructions and techniques have beenemployed for introducing such turbulence to the induction system, theseturbulence inducing devices all substantially restrict the ability ofthe engine to breath under high speed, high load conditions.

There have, therefore, been proposed arrangements that incorporate acontrol valve in the induction passage which has the effect of not onlychanging the cross sectional area and, accordingly, the velocity of thecharge entering the combustion chamber but additionally varying thedirection in which the charge enters the chamber. Such devices canimprove the efficiency of the engine at low and mid ranges withoutadversely affecting the high performance characteristics of the engine.Examples of such flow controlling induction systems may be found in theco-pending applications of Yoshiharu Osaka entitled "Tumble ControlValve For Intake Port", Ser. No. 834,604, filed Feb. 12, 1992 and"Intake Air Control System For The Engine", Ser. No. 893,111, filed Jun.3, 1992, which applications are assigned to the Assignee hereof.

The constructions shown in those patent applications are extremelyeffective in providing good running over a wide variety of enginerunning characteristics. It has been found, however, that theperformance of the engine both in the terms of exhaust emission control,fuel economy and engine output performance can vary significantly withthe position of the control valve. Said another way, it has been foundthat the optimum position of the control valve for given runningconditions varies with a number of parameters.

It is, therefore, a principal object to this invention to provide animproved induction control system for an engine.

It is a further object to this invention to provide an improved engineinduction system incorporating a control valve and an improvedarrangement for positioning the control valve.

In connection with the control of control valves of the type shown inthe aforenoted patents, it has also been found that under certain rangesof engine running conditions there is an advantage in maintaining thecontrol valve in either its flow restricting or its fully openedposition, even though this condition may not be the optimum for theactual engine condition. By maintaining the control valve in one of itspositions under a range of running operations, it has been foundpossible to improve fuel economy and/or performance depending upon othercharacteristics of the engine.

It is, therefore, a still further object to this invention to provide animproved induction system incorporating a control valve and a strategyfor maintaining the control valve in one of its positions during a rangeof engine conditions.

With spark ignited engines, it is also a practice to vary the timing offiring of the spark plug in response to engine running conditions, mostnormally engine speed and/or load. For example, under low speed, lowload conditions the spark is normally fired at an advanced condition soas to insure that full combustion can occur at the appropriate time.However, as the speed of the engine increases, the amount of sparkadvance is normally retarded from the low speed condition although thespark plug is always fired before top dead center. Of course, theoptimum spark timing will vary depending upon a number of factors.

It has been further found that if conventional spark timing is employedin conjunction with an engine having an induction system control valve,then under some ranges of control valve operation the spark timing maynot be optimum. For example, it has been the practiced, as noted above,to advance the spark timing when operating at low speed, low loadconditions because of the low rate of flame propagation in thecombustion chamber. However, when a control valve is employed forredirecting the charge and creating turbulence in the combustionchamber, then the conventional spark timing will not be appropriate.

It is, therefore, a still further object to this invention to provide animproved spark control arrangement for an engine having a control valvewherein the spark timing is varied in relation to the control valveposition.

Although it may be possible, as previously noted, to determine theoptimum position of the induction control valve for given runningconditions, transient conditions present a different type of problem.For example, under high speed, high load conditions it is normallydesirable to maintain the control valve in its opened position whileunder low speed, low load conditions it is desirable to maintain thecontrol valve in its closed or flow controlling position. However, whendecelerating from a high speed, high load condition due to rapid closureof the throttle valve or a sudden decrease in operator demand, then thethrottle valve or operator throttle control will indicate a low speed,low load condition while the engine is still operating at high speed.Under such conditions, it has been desirable to maintain the controlvalve in its fully opened position even though the speed controlposition may indicate a different running condition.

It is, therefore, a still further object to this invention to provide aninduction system having a control valve and improved strategies foroperating to provide better performance under certain types of transientconditions.

In addition to the positioning of the control valve under extremedeceleration conditions, as aforenoted, it is also desirable to changethe spark timing when the control valve is held in its fully openedposition and independently of the other sensed engine conditions so asto improve fuel economy.

It is, therefore, a still further object to this invention to provide animproved spark control system for an engine having a control valve inits induction system and which control valve is held in one position inresponse to a sudden change in operator demand.

Another condition when the positioning of the control valve may bedetermined primarily by one engine condition other than those normallysensed, is when the engine is stopped. Normally when the engine isstopped, the throttle control will be positioned in a position thatwould call for the control valve also to be positioned in its flowrestricting position. Depending upon the geometry of the inductionsystem and the type of charge former employed, such closure of thecontrol valve could trap residual condensed fuel in an upstream locationin the induction system. This trapped fuel could give rise to certainproblems when the engine is being restarted. On the other hand, theremay be some types of engine configurations or some conditions when it isdesirable to maintain the control valve in its closed position when theengine is shut off.

It is, therefore, a still further object to this invention to provide animproved arrangement for operating the control valve upon the stoppingof the engine to place it in one of extreme positions and regardless ofthe other engine conditions which may be sensed.

As has already been noted, during starting of the engine and whenoperating at low speeds and low loads, it is desirable to position thecontrol valve in a closed or flow restricting position so as improveturbulence and redirect the air flow in the combustion chamber. However,there may be some instances when even this is not desirable.

For example, if the engine is provided with a catalytic convertor orother type of device for treating the exhaust gases, it is desirable toinsure that this exhaust treatment device is at its operatingtemperature or brought to that temperature quickly during cold startingand warm up. This is because catalytic convertors must be at theiroperating temperature before they become effective. Thus, under somecold start up conditions it may be desirable to promote other than thebest combustion efficiency in the engine so that a fuel rich mixture maybe delivered to the catalytic convertor so as to cause it to heat morerapidly.

It is, therefore, a still further object to this invention to provide animproved induction system and control device therefore that will assistin cold starting warm up.

SUMMARY OF THE INVENTION

Various features of the invention are all adapted to be embodied in aninternal combustion engine that has a combustion chamber and an intakepassage that communicates at a valve seat with the combustion chamber. Acontrol valve is positioned within the intake passage and is moveablebetween an opened position wherein the flow into the combustion chamberis substantially unrestricted and in a first direction and a closedposition wherein the flow into the combustion chamber is restricted toincrease the flow velocity and to redirect the flow from the firstdirection.

In accordance with a first feature of the invention, means are providedfor operating the control valve between the closed position, a pluralityof intermediate positions and an opened position in response to sensedengine conditions, which conditions are sensed by one or moreappropriate sensors.

In accordance with another feature of the invention, means are providedfor moving the control valve between the positions in response to anengine condition. A spark plug is also provided for firing a charge inthe combustion chamber. Means are provided for firing the spark plug inaccordance with a first timing curve when the control valve is in one ofits positions and in accordance with a second, different timing curvewhen the control valve is not in that one position.

A further feature of the invention employs means for positioning thecontrol valve in a position dependent upon operator demand and forpositioning and retaining the control valve is one of the positions upona sudden change in operator demand.

In accordance with another feature of the invention, means are providedfor sensing an engine condition for operating the control valve betweenits positions. Starting means are incorporated for starting the engineand means hold the control valve in one of the positions during theoperation of the starting means and independently of the enginecondition sensed.

In accordance with another feature of the invention, means are providedfor sensing an engine condition for controlling the position of thecontrol valve. The control valve is held in one of its positions whenthe engine is stopped and regardless of the engine condition.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of a portion of an internal combustionengine having an induction system constructed and operated in accordancewith an embodiment of the invention, with a portion broken away to moreclearly show the construction.

FIG. 2 is an enlarged cross sectional view taken through one of theintake valves and shows the control valve in its closed, flowcontrolling position.

FIG. 3 ms a cross sectional view taken along the line 3--3 of FIG. 2.

FIG. 4 is a cross sectional view taken along the line 4--4 of FIG. 1 andshows the control and throttle valves in the position shown in FIG. 1 asat low speed, low load running conditions.

FIG. 5 is an enlarged perspective view showing how the control valvecooperates with the rectifier plate in one of the intake passages whenoperating at low speed and low load conditions.

FIG. 6 is a map showing the relationship of the control valve positionin response to engine speed and operator control throttle valveposition.

FIG. 7 is a block diagram showing the control routine for operating thecontrol valve and automatic throttle valve.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

Referring now in detail to the drawings and initially to FIGS. 1 through5, an internal combustion engine constructed and operated in accordancewith an embodiment of the invention is shown partially and is identifiedgenerally by the reference numeral 11. Since the invention dealsgenerally with the induction system for the engine 11 and the method ofcontrolling the induction system, only that portion of the engine andthat portion of the induction system associated with a single cylinderof the engine 11 is depicted because it is believed obvious to thoseskilled in the art how to practice the invention with any type of engineand engines having any number of cylinders and any cylinderconfiguration. Facets of the invention also may be employed with rotaryas opposed to reciprocating engines.

The engine 11 is comprised of a cylinder block 12 having cylinder bores13 formed by pressed or cast-in liners 14. Pistons 15 are reciprocallysupported in the cylinder bores 13 and connected to a crankshaft (notshown) that is rotatably journalled within a crankcase 16 by meansconnecting rods 17.

A cylinder head, indicated generally by the reference numeral 18 isaffixed in any known manner to the cylinder block 12 and has a cavity 19formed in its lower face for each of the cylinder bores 13 so as to formwith the cylinder bores 13 and pistons 15, the respective combustionchambers of the engine.

A charge forming and induction system is provided for supplying afuel/air charge to each of the combustion chambers 19 and this includes,in the illustrated embodiment, a carburetor 21 of the sliding pistontype with the sliding piston being indicated by the reference numeral22. This sliding piston 22 is positioned in an induction passage 23 ofthe carburetor 21 upstream of a manually operated throttle valve 24. Ametering rod 25 is connected to the piston 22 so as to vary both theamount of fuel flowing and the effective cross sectional area of theinduction passage 23 as the throttle valve 24 is opened and closed.

Interposed between the carburetor 21 and the induction passages, to bedescribed, of the cylinder head 18 is a throttle body 26 which is formedwith a common inlet portion 27, shown in most detail in FIG. 4, in whicha throttle control valve assembly, indicated generally by the referencenumeral 28 is positioned. The throttle control valve assembly 28includes a control valve shaft 29 on which one butterfly type throttlevalve 31 is affixed so as to selectively open or close the flow througha secondary induction passage 32 formed in the cylinder head 18 on theintake side thereof. Parallel to the secondary induction passage 32 is aprimary induction passage 33 which extends generally parallel to thesecondary induction passage 32 with the induction passages 32 and 33generally being of the same configuration having a first generallydownwardly inclined portion 34 that merges into a second portion 35 thatextends generally parallel to the cylinder bore axis with the portions34 and 35 being joined by a curved bight 36. The configuration of theinduction passages 32 and 33 is such that a charge entering thecombustion chamber 19 through the induction passages 32 and 33 will havesubstantially low flow resistance and thus provide a high volumetricefficiency. However, because of this configuration, low turbulence isgenerated under low and mid range running conditions which can causeproblems in efficient combustion, as aforenoted. A construction, whichwill be described, is provided for controlling the effective flow areasof the induction passages 32 and 33 and also for blocking the flowthrough the induction passage 32 so as to create more turbulence in thecombustion chamber 19 and to provide a different flow pattern therein.

The portions 35 of the induction passages 32 and 33 terminates atrespective valve seats 37 which are pressed into the cylinder head 18 ina well known manner. A pair of intake poppet valves, each indicatedgenerally by the reference numeral 38 have respective head portions 39that engage the valve seat 37 so as to control the flow entering thecombustion chambers 19. The valves 38 further have valve stems 41 thatare slideably supported within valve guides pressed into the cylinderhead. Coil compression springs 42 engage keeper retainer assemblies 43fixed to the upper ends of the valve stems 41 for urging the valves 38to their closed positions.

Thimble type tappets 44 are slideably supported within bores of thecylinder head and engage the keeper retainers 43 for opening the intakevalves 38. An overhead mounted intake camshaft 45 is journalled in anappropriate manner in the cylinder head 48 and has cam lobes thatoperate the thimble tappets 44 to open the intake valves 38 in a wellknown manner.

A charge which has entered the combustion chambers 19 from the inductionsystem as thus far described is fired by means of spark plugs 46 mountedcentrally in the cylinder head 18. The spark plugs 46 are fired by anysuitable ignition system that provides timing curves, as will bedescribed.

A pair of exhaust passages 47 are formed in the cylinder head 18 on theside opposite the induction side thus far described. The exhaustpassages 47 terminate in respective exhaust valve seats 48 and the flowthrough them is controlled by means of a pair of exhaust poppet valves49, each having a valve head 51 for cooperating with the valve seats 48and a stem portion 52. The stem portions 52 are slideably supported invalve guides that are pressed into the cylinder head 18. Coilcompression springs 53 engage keeper retainer assemblies 54 fixed to thevalve stems 52 for urging the valves 49 to their closed positions.Thimble tappets 55 are slideably supported within bores of the cylinderhead 18 and are engaged by the lobes of an exhaust camshaft 56 foropening and closing the exhaust valves 49.

The intake camshaft 45 and exhaust camshaft 56 are journalled in thecylinder head assembly 18 by means including respective bearing caps 57and 58 which are affixed to an upwardly facing surface 59 of thecylinder head 18. The camshafts 45 and 56 are contained within a camcover 61 that is affixed to the cylinder head 18 in a conventionalmanner. The intake and exhaust camshafts 45 and 56 are driven from theengine crankshaft at one half crankshaft speed, as is well known in thisart.

Except for the throttle control valve 31 as thus far described, theengine 11 may be considered to be conventional. As noted, however, theinduction system, although providing good efficiency for maximum speedperformance, will not provide good combustion under low or mid rangerunning due to the lack of turbulence in the combustion chamber underthese conditions. Therefore, a system now to be described and whichincludes the throttle control valves 31 is provided for inducingturbulence and high velocity in the combustion chamber under certainrunning conditions.

The cylinder head 18 is formed with a transversely extending bore 62that is disposed at the bight section 36 of the induction passages 32and 33. A control valve, indicated generally by the reference numeral63, has a cylindrical portion 64 that is rotatably journalled in thebore 62 and which extends across the bight section 36 of the inductionpassages 32 and 33. This control valve 63 is provided with a pair ofcut-outs 64 which form an opening passage which has a configurationwhich is complimentary to and forms a continuation of the bight section36 when the control valve 63 is in its fully opened position so as tonot interfere with the flow through the induction passages 32 and 33 norto offer any flow resistance to the flow therethrough. Thus, when tilecontrol valve 63 is held in its opened position, as will be described,there is no flow restriction nor any flow redirection.

When the control valve 63 is rotated to its fully closed position asshown in the Figures, however, then the intake charge flowing throughthe induction passages 32 and 33 will be redirected toward the side ofthe valve seats 37 adjacent the center of the cylinder bore 13 so as tocause the intake charge to be delivered in a path shown by the brokenline in FIG. 1 so as to generate a tumble action in the cylinder bore13. This tumble action is a swirl about a horizontal rather than avertical axis and promotes turbulence in the combustion chamber. Inaddition, since the effective flow areas of the induction passages 32and 33 are reduced by the control valve 63, the velocity of the chargeentering the combustion chambers 19 will be greater than if the controlvalve 63 were opened under this running condition and this furtherpromotes turbulence. The increased turbulence improves fuel/air mixingand also causes a more rapid flame propagation once the spark plug 46 isfired. Thus, complete combustion will be insured due to the use of thecontrol valves 63.

To provide further augmentation, there is provided a rectifier plateassembly, indicated generally by the reference numeral 65 and having aconstruction which is shown in most detail in FIG. 5. This rectifierplate 65 is disposed, in the illustrated embodiment, only in the primaryinduction passage 33 (the one without the flow controlling throttlevalve 31). The rectifier plate 65 has a curved lip portion 66 thatextends into the induction passage portion 35 and across the bight 36 ingenerally parallel fashion so as to divide this induction passage intotwo portions. When the control valve 63 is in its fully closed positionas shown in FIG. 5, the plate 66 will be engaged by the cut-out surface64 and thus no flow on the opposite side is permitted. The plateportions 66 is formed with a recess 67 so as to clear the stem portion41 of the associated intake valve 38.

The rectifier plate 65 has a ring-like base portion 68 that is receivedwithin the bore in the cylinder head in which the valve seat 37 is pressfitted and thus this serves to maintain the rectifier plate 65 in itsposition.

The mechanism for controlling both the control valve 63 and the flowcontrolling throttle valve 31 will now be described, by particularreference to FIG. 1 although certain of the components for providingthis actuation also appear in FIG. 2. There is provided a pulley 69 thatis affixed to an exposed end of the control valve 63 and particularlyits shaft portion 64. A wire actuator 71 connects this pulley to afurther pulley 72 connected to a servo motor that is controlled by meansof an ECU 73 through a control line 74. In a similar manner, a pulley 75is affixed to the throttle control valve shaft 29 and is driven from apulley 76 of a further servo motor 77 by a respective wire actuator 78.The servo motor 77 is also controlled by the ECU 73 as indicated by theschematic control line 79.

The ECU 73 receives input signals indicative of certain engine runningconditions and certain other conditions, as will be described. In theillustrated embodiment, one of these conditions is a speed signal 81which is generated from an input received from a crankshaft sensor so asto convert these sensor pulses into an indication of speed which istransmitted to the ECU 73 through a connection 82. In addition, a loadinput is delivered to the ECU 73 which is, in this embodiment, generatedby a throttle valve position sensor 83 that outputs a signal as shownschematically at 84 to the ECU 73 which is indicative of the position ofthe throttle valve 24 and, accordingly, the load on the engine. Asopposed to a throttle position sensor, the load signal may be deliveredfrom an air flow sensor, induction system vacuum or any other known typeof arrangement.

The position of the control valve 63 as set by the ECU 73 is derivedfrom information contained within a map, which map is shown in FIG. 6and which is generated in a manner as will be described. This mapindicates the respective positions of the control valve 63 as shown onthe "Z" axis in relation to throttle valve opening as shown on the "X"axis and engine speed as shown on the "Y" axis. This map is generated soas to contain data arrived at by actual testing of an engine at eachengine speed and throttle valve opening, with the control valve 61 beingrotated to a position wherein maximum power is generated. It should benoted that the map of FIG. 6 is derived from an engine that preferablyprovides better high speed performance although the shape of the map canbe altered, as will become apparent to those skilled in the art, so asto provide optimum performance under all conditions.

As an example of how the three dimensional map of FIG. 6 is generated,assuming that the engine is running at a condition wherein the throttlevalve opening of the throttle valve 24 is set at the position b₁, whichis approximately half way between fully opened and fully closed and theengine is operating at a speed al at a speed which is something greaterthan half way between idle and full speed operation, the control valve63 is gradually opened from its fully closed position until a positionwhen the maximum power output or torque is read, this being the openingc₁. Openings of the control valve 63 beyond the position c₁ at these setthrottle and engine speed openings b₁, a₁, will not produce any increasein power.

That is, as the control valve 63 is opened under these conditions, theamount of tumble and velocity increase of the intake charge is graduallyreduced and under these conditions, the power of the engine willgradually increase as will fuel economy. Eventually, however, there willbe a point where further opening of the control valve 63 will notprovide any increase in power and, accordingly, the point c1 for theposition of the control valve 63 is chosen when the throttle opening isat b₁ and the engine speed is at a₁.

It should be noted that the same curve could be generated if rather thanstarting out with the control valve fully closed and opening it, thatthe procedure begin with full opening of the control valve and graduallyclosure of it. If this procedure would be followed, it would be foundthat continued closing of the control valve would not produce anydecrease in engine power until the point c1 was passed and then thepower output of the engine would gradually drop off.

Thus, for most operating conditions the three dimensional map is chosenby determining the condition of the control valve for given enginethrottle settings and speed where the maximum power is achieved.However, there are certain engine running conditions when the controlvalve 63 may be maintained in its fully closed position over ranges ofengine speed and throttle opening and also where the control valve 63may be maintained in its fully opened position over ranges of enginespeed and throttle opening without adversely affecting performance.

For example in a range where the engine speed is, for example, at thespeed a2, there is a throttle opening b_(s) of the throttle valve 24below which there is no advantage to opening the control valve 63 at allbecause the engine power output will not be increased. That is, untilthe throttle opening at the speed a₂ reaches the throttle opening b_(s)there is no reason to open the control valve. Hence, in the domain tothe right of b_(s) the control valve 63 is maintained in its fullyclosed position. Also, at the speed a₂ and when the throttle opening isopened to the degree b_(o), any closure of the control valve 63 willprovide an immediate drop off in power and hence for throttle openingsgreater than b_(o) at the engine speed a₂, the control valve 63 ismaintained in its fully opened position.

The characteristics of the map of FIG. 6 will depend on a number ofother features such as the valve timing for the engine, the opening andclosing position of the intake control throttle 31, the portconfiguration, etc. As has been noted, FIG. 6 is indicative of the typeof map which would result in an engine that designed primarily toachieve high maximum power output. An engine that was oriented more toobtain better low and mid range speed would have a different map ofcourse.

In addition to containing the information from the map of FIG. 6, theECU 73 also contains information to control the timing of firing of thespark plugs 46. As has been previously noted, with conventional enginesit is the practice to advance the spark timing at low speed, low loadconditions to accommodate the fact that combustion takes longer underthese conditions than under high speed conditions. Such conventionalignition timing further retards the spark advance as the amount ofintake air increases and reaches the ideal curve when the intake airamount is high. However, since the control valve 63 is provided in thisarrangement, a conventional spark timing would provide too advancedspark timing under low speed, low load conditions. Because of the use ofthe control valve 63, the spark timing may, at extreme low speed, lowload conditions, be delayed from about 10° from the normal spark timing.

Thus, the ECU 73 is provided with not only a first ignition timing mapthat has the conventional engine timing for a system without a controlvalve, but also has a second ignition timing map which is set for theeffect of the control valve 63 being in the closed or partially closedpositions. There are, however, certain conditions when it is desirableto switch from the second map to the first map and some of thoseconditions will now be described. It will be understood that thoseconditions are primarily transient conditions or certain specificrunning conditions and under normal conditions, the second ignitiontiming map will be employed so as to improve fuel consumption underconditions when the intake air amount is low (engine load is low).

One specific transient condition wherein the normal spark timing curveas opposed to the second timing curve is desirable is under conditionsof extreme deceleration. Under this condition, the operator may closethe throttle valve 24 very rapidly so as to cause a reduction in vehiclespeed but during initial closing of the throttle valve 24, the enginespeed will still be quite high. Thus, because the engine speed is higherthan a predetermined speed even though the throttle opening is closed,it is desirable to maintain the control valve 23 also in a fully openedposition, as will be described later, even though the position of thethrottle valve 24 would call for a close position of the control valve63. Thus, although the ECU 73 would normally believe that under such acondition the control valve should be fully closed and second sparktiming curve should be followed, the ECU 73 will hold the control valve63 in its fully opened position and also will use standard ignitiontiming from the first timing curve. The condition of rapid throttleclosing and deceleration from high speed may be sensed by either adeceleration sensor or a sensor that determines that the throttle valve24 is being closed at a rapid speed and the engine speed is still heldhigh. Suitably sensors and arrangements for determining such rapiddeceleration are well known for other purposes.

Another case in which the ECU 73 controls the control valve 63 andignition timing other than in response to the position of the throttlevalve 24 and the engine speed solely, is a condition during cold startand warm up and if a catalytic convertor or other similar exhausttreatment device is employed for further purifying the exhaust gasesissuing from the exhaust passages 47. If a catalyst is employed, it isdesirable to insure that the catalyst reaches its operating temperaturevery quickly so as Go be fully effective. However, if the control valve63 and spark timing are set only in response to engine running speed andthrottle valve opening, then the engine will operate efficiently andthere will be very little unburned fuel in the exhaust gases. Althoughthis is normally a desirable result, when the exhaust gas temperature islower than a predetermined value and the catalyst is, therefore,unheated it is decided by the ECU 73 that the engine is in a cold engineoperation state.

Under this condition, ignition is delayed from the standard one (thesecond ignition map is employed) and the control valve 63 is held fullyopened even through the intake air amount is low. Because of such acombined action, combustion is not as complete and there will be moreunburned fuel in the exhaust gases. This will cause an afterburningeffect in the exhaust pipe and the catalyst temperature to rise muchmore rapidly so as to function normally in a short period of time.Hence, by so varying both the ignition timing and the opening of thecontrol valve 63 from that called for by the actual engine speed andengine load, quicker warm up of the catalyst is achieved.

A preferred sequence of operation of the air control throttle valve 31will now be described and this operation may be considered inconjunction with the map of FIG. 6 although that map does not show theoperation of the throttle control valve 31 which, as has been noted,controls the air flow through the secondary induction passage 32.

Under low speed, low load conditions and those conditions when theintake air control valve 63 is in its closed position as shown in thesolid line view of the Figures, the throttle control valve 31 is alsomaintained in its fully closed position. As a result, the air flow intothe cylinders and specifically the combustion chambers 19 takes placeonly through the primary induction passage 33. This provides not onlythe tumble action previously described, but also imparts a swirl to theintake charge about a vertically extending axis due to the fact that theprimary induction passage 33 is offset to one side of the spark plug 46as shown in FIG. 2. Hence, the motion of the intake air will be furtheraccelerated and combustion will be improved.

When operating at the medium speed and medium load positions and theamount of intake air required is medium, the intake air control valve 63will be rotated toward its open position in accordance with the map ofFIG. 6. However, at least during this initial opening, the throttlecontrol valve 31 is maintained either in a fully closed or a partiallyclosed condition depending upon the degree of intake air required.Hence, there will be still some swirl in addition to tumble generateduntil the throttle control valve 31 is fully opened.

Under high speed, high load conditions, the control valve 63 andthrottle control valve 31 are both held their fully opened position andthe induction system functions that of a normal engine.

The control routine for controlling the control valve 63 will now bedescribed by reference to FIG. 7 with additional reference to FIG. 6.However, it should be noted that before the engine is started, there isa further condition when the control valve 63 is positioned in aposition that is independent of the opening of the throttle valve 24 orother load and also the speed of the engine. Note that at low throttlevalve openings and low speed, the control valve 63 would normally beclosed. If when the engine is shut off the control valve 63 is closed,fuel may condense in the induction passages 32 and 33 and this condensedfuel will be trapped in place in the induction passages if the controlvalve 63 is placed in its fully closed position, which would be normallythe case with this engine condition. In order to avoid this, the ECU 73may be programmed so as to place the control valve 63 automatically inan opened position when the engine is shut off. This can be convenientlydone by sensing the condition of the ignition switch or a kill switch ofthe engine. However, immediately upon starting of the engine, then thecontrol valve 63 may be moved to its closed position unless the coldstarting feature for heating the catalytic convertor, as aforedescribed,is to be employed.

Alternatively to the aforedescribed control routine, the ECU 73 may beprogrammed to hold the control valve 63 in a fully closed position whenthe engine is shut off. It will also insure that the control valves willbe fully opened to heat the catalyst in the event of cold starting withsuch an arrangement, the closure of the control valve upon the startingoperation can be controlled primarily by temperature if the catalystheating feature is to be employed.

Referring now to FIG. 7, the program begins with the engine is startedand then moves to the step S1 so as to read engine speed by the sensor81 and engine load by the throttle valve position sensor 83. As has beenpreviously noted, other methods for sensing engine load such as airflow, manifold vacuum or the like may be employed in lieu of throttlevalve position. Once these readings are taken, they are transmitted tothe ECU 73, this all occurring at the step S1.

The program then moves to the step S2 where the ECU 73 reads the map ofFIG. 6 and determines the appropriate control valve setting for thecontrol valve 63. This procedure, although described generally above,will be described in some detail later.

The program then moves to the step S3 wherein the ECU 73 outputs thecontrol valve signal through the control 74 so as to position thecontrol valve 63 in its desired position as read from the map. The ECUalso will output a signal through the line 73 to the servo motor 72 forpositioning the throttle control valve 31 in accordance with a separatemap for this control and as was generally described.

Referring now again to FIG. 6, it will be seen that as long as theengine speed is below a speed a₃, the control valve 63 is maintained inits fully closed position regardless of the condition of the throttlevalve 24. This is done so as to permit the operator to blimp thethrottle if he desires without causing the control valve to move backand forth. If desired, the speed a₃ may constitute the idle speed of theengine.

When the engine speed is above the speed a₃ but below the speed a₁, thecontrol valve 63 is held in its closed position until the throttle valveis opened at a point which, according to the map of FIG. 6, indicatesthat opening of the control valve will improve the performance. This isas indicated by the boundary opening b_(s) which varies depending uponthe particular condition with b_(s) at the engine speed of a₂ beingindicated on the map. As may be seen in FIG. 6, the fully closedboundary opening b_(s) is set so as to be smaller than the fully openedboundary opening b_(o) but the curve connecting them is inclined andthis inclination angle becomes greater at the higher engine speed range.This also shows that when closing the throttle valve 24 the intake aircontrol valve 63 is closed earlier as the engine speed becomes higherand the contrary is true when opening the throttle valve. That is, underthis condition the intake control valve 63 is rotated so as to openlater as the engine speed becomes higher.

Both the fully closed boundary opening b_(s) and the fully openedboundary opening b_(o) are set to be greater as the engine speed becomeshigher so as to mean that the throttle valve opening range where theintake air control valve 63 is kept fully closed is set to be wider asthe engine speed becomes higher and the throttle valve opening rangewherein the intake control valve 63 is kept fully opened is set narroweras the engine speed becomes higher. As has been previously noted, thisis done with this particular embodiment because this embodiment isdesigned for engines that have their emphasis on high power, highoutput. Of course, these conditions can be varied depending upon theoverall performance which is desired for the engine.

Also, it is desirable to minimize the movement of the control valve 63and as long as the engine speed in this embodiment is higher than theengine speed a₁, then the control valve 63 will be held fully openedregardless of the actual throttle opening. This has the same benefit askeeping the intake control valve 63 fully closed when the engine speedis below the speed a₃. This fixed positioning of the control valve 63under these extreme engine speed ranges minimizes the fluxuation of theoperation of the control valve 63 from that which would occur if theactual curves shown on the map of FIG. 6 were to be followed rather thanhaving the cut-off points as described.

This holding of the control valve 63 in its opened position when theengine speed is above the speed a₁ and regardless of the throttleopening also make sure that they control valve 63 will be opened andheld open on extreme decelerations. This will improve engine performanceand engine breaking while minimizing deterioration in fuel efficiencywhen the engine is in a breaking mode.

It should be readily apparent from the foregoing description that thedescribed control routines are effective in providing efficient andexcellent engine operation under all running conditions whileaccommodating certain types of transient conditions which mightotherwise present difficulties. Of course, the described construction isonly that of preferred embodiments of the invention and various changesand modifications may be made without departing from the spirit andscope of the invention, as defined by the appended claims.

We claim:
 1. An internal combustion engine having a combustion chamber,an intake passage communicating at a valve seat with said combustionchamber, a control valve positioned within said intake passage andmoveable between an opened position wherein the flow into saidcombustion chamber is substantially unrestricted in a first directionand a closed position wherein the flow into said combustion chamber isrestricted to increase the flow velocity and to redirect the flow fromsaid first direction, means for moving said control valve between saidpositions in response to engine conditions, spark plug means for firinga charge in said combustion chamber, and means for firing said sparkplug in accordance with a first timing curve when said control valve isin one of its positions and in accordance with second, different timingcurve when said control valve is not in said one position.
 2. Aninternal combustion engine as set forth in claim 1 wherein the oneposition of the control valve is the closed position of the controlvalve.
 3. An internal combustion engine as set forth in claim 2 whereinthe first timing curve provides a retarded spark timing from the secondtiming curve at low speed, low load conditions.
 4. An internalcombustion engine as set forth in claim 3 wherein the sensed enginecondition is load.
 5. An internal combustion engine as set forth inclaim 4 wherein the induction system is further provided with a manuallyoperated throttle valve in said intake passage upstream of said controlvalve and wherein the load is determined by the position of the throttlevalve.
 6. An internal combustion engine as set forth in claim 3 whereinthe sensed engine condition is speed.
 7. An internal combustion engineas set forth in claim 3 wherein the means for sensing engine conditionincludes means for sensing two different engine conditions.
 8. Aninternal combustion engine as set forth in claim 7 wherein the controlvalve is held in one of its positions when one of the sensed engineconditions is below a predetermined first value and regardless of themagnitude of the other sensed engine condition.
 9. An internalcombustion engine as set forth in claim 8 wherein the control valve isheld in the other of its positions when the one condition is above asecond predetermined condition and regardless of the value of the othercondition.
 10. An internal combustion engine as set forth in claim 9wherein the one condition is speed.
 11. An internal combustion engine asset forth in claim 10 wherein the control valve is held in a closedposition when the engine is below a first predetermined engine speed.12. An internal combustion engine as set forth in claim 11 wherein thecontrol valve is held in its open position when the speed of the engineis greater than a second predetermined engine speed.
 13. An internalcombustion engine as set forth in claim 12 wherein the other enginecondition is load.
 14. An internal combustion engine as set forth inclaim 13 wherein the induction system is further provided with amanually operated throttle valve in said intake passage upstream of saidcontrol valve and wherein the load is determined by the position of thethrottle valve.
 15. An internal combustion engine as set forth in claim13 wherein load is sensed by determining the air flow to the engine. 16.Am internal combustion engine as set forth in claim 13 wherein the loadis sensed by sensing the pressure in the intake passage.
 17. An internalcombustion engine as set forth in claim 7 wherein one of the sensedconditions is operated demand.
 18. An internal combustion engine as setforth in claim 3 wherein the engine is provided with an exhaust systemhaving a catalytic device.
 19. An internal combustion engine as setforth in claim 18 wherein the control valve is held in its openedposition upon starting and if the temperature of the catalytic device isbelow a predetermined temperature.
 20. An internal combustion engine asset forth in claim 19 wherein the first timing curve is employed forsetting the spark timing when the control valve is held in its openposition upon starting and if the temperature of the catalytic device isbelow the predetermined temperature.